There are two major types of cells grown in vitro: suspension cells (anchorage-independent cells); and adherent cells (anchorage-dependent cells). Suspension or anchorage-independent cells can proliferate, in vitro, without being attached to a surface. In contrast, adherent or anchorage-dependent cells require attachment to a surface in order to grow in vitro.
Suspension or anchorage-independent cells have typically been grown in vitro in glass, metal, or hard plastic vessels. There have been disadvantages, however, to using these cell culture vessels. Glass and metal cell culture vessels are expensive and require maintenance, as they are not disposable or sterile. In order to maintain a sterile or aseptic environment for cell culture, the vessels require sterilization, usually by autoclave. Therefore, the cell culture vessels must be washed and sterilized prior to and/or subsequent to their use. In addition, because glass and metal cell culture vessels are not disposable, it is necessary to have adequate space for storage of the glass and metal vessels. Thus, as glass, metal, and hard plastic cell culture vessels are expensive, not disposable, and require extensive maintenance, there has been a need for a cell culture vessel that is inexpensive, disposable, collapsible, and pre-sterilized.
Further, for anchorage-independent biological cells to grow, the cells require constant suspension. In order for the cells to remain suspended, a cell culture vessel must have means for keeping the cells suspended. Many cell culture vessels have an impeller with blades that rotate to keep cells suspended. If the impeller rotation or movement is too strong or the blades are too rigid or too long, the cells may be sheared by the force of the impeller or blades. Likewise, if the impeller rotation or movement is too weak or the blades are too short, the cells may not remain suspended. Therefore, there is a need for an improved cell culture vessel which provides gentle stirring to prevent shearing and keep cells suspended.